Express your answer as a mixed number simplified to lowest terms. $20\dfrac{5}{12}-3\dfrac{7}{9} = {?}$
Explanation: Find a common denominator for the fractions: $= {20\dfrac{15}{36}}-{3\dfrac{28}{36}}$ Convert ${20\dfrac{15}{36}}$ to ${19 + \dfrac{36}{36} + \dfrac{15}{36}}$ So the problem becomes: ${19\dfrac{51}{36}}-{3\dfrac{28}{36}}$ Separate the whole numbers from the fractional parts: $= {19} + {\dfrac{51}{36}} - {3} - {\dfrac{28}{36}}$ Bring the whole numbers together and the fractions together: $= {19} - {3} + {\dfrac{51}{36}} - {\dfrac{28}{36}}$ Subtract the whole numbers: $=16 + {\dfrac{51}{36}} - {\dfrac{28}{36}}$ Subtract the fractions: $= 16+\dfrac{23}{36}$ Combine the whole and fractional parts into a mixed number: $= 16\dfrac{23}{36}$